60 WorsdelL— The Structure and Morphology of the 'Ovule! 
These views may be termed (i) the axial, (2) the foliolar , and (3) the sui 
generis theory respectively. 
The most striking of the arguments which, during a period of some 
seventy years, have been advanced in support of each of the above theories 
will now be presented. 
Historical Sketch. 
As regards the first of these views, the shoot-, bud-, or axial-theory — 
whichever term most appeals to the reader — appears to have been the one 
prevalently held about the middle of the last century (Fig. 2). Its most 
weighty supporter is undoubtedly the great German botanist Alexander 
Braun (15), who, nearly twenty years after Schleiden, in a paper dealing 
more particularly with certain phenomena in the life-history of Coelebogyne , 
embodies ideas which, at first appearing to support the foliolar-theory of the 
ovule, are eventually seen to practically dispose of this in favour of the axial 
view. ‘ Leaves/ he says, ‘ suppose an axis ; and as the idea that placentae 
are axile in nature as regards the majority of plants has been decisively 
refuted, the notion that ovules are entire leaves also falls to the ground.’ So 
that c the first explanation of ovules must be accepted, viz., that they are 
parts of a leaf, marginal structures, either peculiarly modified teeth, lobes , or 
pinnae of the carpel/ as Roeper and Brongniart stated, but with the recog- 
nition that the ovule must be regarded as something beyond a mere con- 
tinuation of the carpel. But this idea of the ovule as a marginal lobe, &c., 
of the carpel cannot be of universal application, as seen in the case of free 
central placentation and in cases where the ovules are distributed, multi- 
seriately or irregularly scattered on very thick or extended placentae. 
These cases show that ovules are not mere marginal structures, but out- 
growths from the surface, comparable to the normal or abnormal emergences 
of many leaves. He says that numerous observations show that the flowers, 
leaves, or leaf-segments arising on expanded structures in cases of antholysis 
do not represent an entire ovule, but only part of such. There is to be dis- 
tinguished a stalk (Trager), which must be regarded as a portion of the 
carpel, or in rare cases as an independent leaf, and sprouting from this a new 
structure — a bud. In metamorphosed ovules of Adonis autumnalis and 
Nigella Damascena he observed the outer integument expanded into a leaf- 
like structure. He remarks that in these cases there is no reason to regard 
it as part of the carpel, nor for aught else but an independent leaf belonging 
to the ovule (Eiknospe 1 ). c If this is correct, the bud-nature of the entire 
ovule is assured.’ He is not decided as to which, the carpel or the ovule, 
the funicle belongs. The bud-nature of the ovule, the latter being 
1 The terms ‘ Eiknospe,’ * Samenknospe ’ (‘ Egg-bud/ ‘ Seed-bud ’), clearly indicate the prevailing 
view as to the nature of the ovule held in Germany about the middle of the last century. The term 
‘ Eichen ’ (‘ ovule’), as now generally adopted, is preferable. 
